Question

A person standing at some distance from a high tree, throws a stone taking aim at a fruit hanging from that tree. The fruit begins to fall freely at the time, when the person throws the stone. Which of the following is correct?
A. The stone moves above the falling fruit.
B. The stone strikes the fruit if the stone is thrown with a definite velocity.
C. The stone moves below the falling fruit.
D. The stone hits the fruit in all cases.

Answer 1

Hint: Recall the concept of relative velocity and try to imagine the situation. The fruit has just started falling when the stone is thrown by the subject. Also note there’s no mention of the fruit falling just after the stone hits the fruit, thus the situation is simple.

Complete answer:
The question states that the subject has thrown a stone taking aim at a fruit, which has just fallen as the subject throws the stone. Thus, we can say that there exists some relative velocity in the vertical direction between the fruit and the stone. Now see that both of them are falling freely under acceleration $g$ after the occurrence of the event, hence the relative velocity will be always constant and the stone moves above the falling fruit. This will always be the situation.

Hence, the correct answer is option A.

Additional Information: Remember that these above stated concepts work only on Newtonian surfaces such as motion in straight line or in rest , but not on rotating and circulating frames. So it's always to keep in mind the frame of reference while solving a given problem. For instance if this same problem is given with circumstances that the boy throws a stone from a moving car, then we had to change the frame of reference to solve the problem.

Note: Note that these questions can also be asked by giving a few parameters such as time, height of launch of stone, height of tree. With these parameters given, we can calculate the required using the concept of relative velocity.